High rigidity and strength requirements are imposed on bodywork components used in automobile construction. At the same time, however, a reduction in the material thickness is desirable with a view to minimizing weight. High-strength and ultrahigh-strength steel materials, which allow the production of components with very high strength combined, at the same time, with a low material thickness, offer a solution to these inherently contradictory requirements. Strength and toughness properties of a component can be set in a targeted way by suitable selection of process parameters during hot-forming which is customarily used for these materials.
To produce a component of this type with the aid of hot-forming, first of all a plate is cut from a coil, and this plate is then heated to above the microstructure transformation temperature of the steel material above which the material is in the austenitic state, is placed into a forming tool in the heated state and deformed to the desired component shape before being cooled, so as to mechanically fix the desired deformed state, with the component being treated and/or hardened.
Often, the component is subjected to a pre-forming step or a trimming step prior to the actual hot-forming. This is described for example in DE 101 49 221 C1. However, a process of this type can cause problems with regard to corrosion, since a strip coating which is customarily applied is damaged during the pre-forming. Standard pre-forming and trimming of the components is not possible in particular in the case of pre-coated high-strength steels such as Usibor 1500 PC, which has an AlSi coating, since the pre-coating is too brittle and consequently the protection against corrosion would be lost.